CHART OF THE DAY: iPod Touch Is Apple's Sleeper Hit

While Apple's iPhone has been a runaway hit, the iPod touch remains a stealthy success story.

It's easy to follow cumulative iPhone sales by Apple's quarterly reports. But while Apple doesn't typically break out iPod sales by type, it often gives hints, which can help us track iPod touch sales.

The most recent: During Steve Jobs' iPad unveiling last week, he revealed that Apple had sold 75 million iPhones and iPod touches so far. Apple sold 42.5 million iPhones through the end of 2009, which could have reached around 44 million by the end of January. This suggests iPod touch sales could be up to 31 million by the end of January.

Twice last year, Apple gave more concrete information about iPod touch sales. Since then, it's clear that while the iPhone has grown faster over the past year, the iPod touch has continued to sell well. (During the December quarter, for instance, iPhone shipments grew 100% year-over-year to 8.7 million, while iPod touch shipments grew slower; 55% year-over-year, Apple said.)

Please Note: Business Insider will never share your information with any other companies. You also have the ability to unsubscribe from these newsletters at any time simply by following the unsubscribe link located at the bottom of each email